Picking station and method for picking with a light grid

ABSTRACT

The invention relates to a commissioning area ( 10 ) comprising a buffer ( 12 ) for order containers ( 14 ) in which items can be commissioned, said buffer ( 12 ) comprising a plurality of adjacent buffer regions for respectively receiving an order container ( 14 ). According to the invention, a beam field ( 16 ) is provided above the buffer ( 12 ) in order to monitor the commissioning of items ( 28 ).

RELATED APPLICATIONS

This is a continuation application of co-pending international patentapplication PCT/EP2005/000204 (WO 2005/068327 A1) which claims priorityof the German application DE 10 2004 002 831.1 filed on Jan. 13, 2004,which is fully incorporated by reference herewith.

BACKGROUND OF THE INVENTION

The present invention relates to a order-picking station having a ordercontainer buffer, wherein articles are pickable into the ordercontainers, the buffer including one or more buffer spaces, particularlybeing arranged next to each other, for respectively receiving one ordercontainer.

The present invention further relates to a method for order-pickingarticles into order containers at a picking station, the ordercontainers being storable within an order container buffer.

RELATED PRIOR ART

Such a method and system are generally known in the prior art.

For example, the document DE 101 36 354 A1 discloses a picking methodand a picking system having a container storage and an associatedstorage and retrieval device for storing and retrieving storagecontainers. Goods to be picked are located within the storagecontainers. The goods to be picked can be of any type of articlesstorable in such a container storage.

The term “container” is not intended to be limited but rather is anexample for a plurality of possible storage units such as trays,palettes and the like. The term “articles” is to be understood as itemswhich can be stored in a container storage and storage containers,respectively. Articles, for example, can be medicaments, tool pieces orthe like, which are ordered, e.g. by customers in arbitrary quantitiesand numbers. Then, the different ordered articles are concatenated as aso-called order, wherein the articles of the order, as a rule, arepicked into one or, should the occasion arise, several order containers,the order containers subsequently delivered to the customer.

A picking station in a picking system is to be understood as a location,where a picking person takes out articles, which are stored within thestorage containers, in order to deposit them subsequently into ordercontainers, which are provided.

An “order container” is to be understood as a container into which goodsand articles, respectively, are put, which are to be picked. An ordercontainer can receive a plurality of different articles until the orderassociated therewith is processed, i.e. until all articles which belongto that order are retrieved from the storage towards the picking stationand have been deposited into the corresponding order container by thepicking person.

Recently, it has gone over to design the picking process according tothe “goods-to-man” principle. According to the “goods-to-man” principlea fixed working area is assigned to the picking person from which he/shemoves away as less and seldom as possible. The articles to be picked areconveyed in storage containers to the picking person. This increases theefficiency of the entire system and fulfills the high ergonomicrequirements which, nowadays, become more and more the focus ofattention.

The storage containers are conveyed to the picking stations by means ofa corresponding conveyor system. The order containers are “parked” atthe picking station directly in front of the picking person. They arejust parked in a so-called order container buffer which can receive aplurality of order containers. The order container buffer is alsoconnected with one, and if necessary, with further conveyor systemswhich convey empty order containers to the picking station andcompletely picked order containers away from the picking station inreaction to a signal. That is why according to the prior art, forexample, a push button is provided at the picking station by which thepicking person can confirm a terminated picking process. Thus, thepicking person, for example, takes out an article from a storagecontainer and puts this article taken into a corresponding ordercontainer. After the deposition of the article into the order container,the picking person can actuate the button in order to confirm thepicking process. A superordinated host system detects this signal andsubsequently judges whether or not the order is completely processed. Ifthe order container is completely picked, then the order container canbe conveyed off.

This procedure involves several disadvantages. On the one hand, theorder containers are conveyed out of the order container buffer whichpossibly are not to be transported off yet. This is particularly thecase, when the picking person actuates the button inadvertently althoughhe/she has not deposited the article to be picked into the correspondingorder container. On the other hand, the button could be actuatedalthough an insufficient number of articles has been put into the ordercontainer so that the order is signaled to the host system as beingcompletely processed although this is not the case.

Further, there is a significant risk of injury. For increasing thevelocity of the picking process it is possible that the picking personputs the article to be picked into the order container with the one handwhile he/she confirms the picking process with the other hand. This canresult in that the picking person has one of his/her hands within theorder container to be picked while simultaneously the conveyance of thisorder container is initiated by the host system. Then the ordercontainer could be moved from the order container buffer which possiblymay result in an injury of the picking person since he/she still has oneof his/her hands within that order container.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a pickingstation as well as a picking method meeting the increased safetyrequirements with respect to both the physical integrity and avoidanceof picking errors.

This object is achieved by a picking station as mentioned at the outsetwherein a beam field is provided above the buffer in order to monitorthe picking of articles.

This object is further achieved by a picking method as mentioned at theoutset, wherein a beam field is generated above the buffer, aninterruption signal is detected which is generated through theinterruption of beams of the beam field, and a first enabling system isoutput which allows the conveyance of an order container from thebuffer.

By providing a beam field above, and particularly directly above, theorder container buffer each picking process can be monitored in twoways. On the one hand, it can be monitored if the picking person stillhas one or, should the occasion arise, both of his/her hands within theorder container while the conveyance of this order container has alreadybegun. On the other hand, it can be monitored if a number of articles tobe picked according to a picking order has been put into thecorresponding order container.

In both instances the beam field is either interrupted by the articlesand/or the hands. This interruption can be used for determining whetherthe picking person has taken out the hands from the order container.When the hands are taken out, the beam field is not interrupted anylonger. Thus, the order container can be conveyed out of the ordercontainer buffer, if necessary. On the other hand, it can be checkedbased on the number of interruptions, which are caused by throwing in orputting in the articles, if the corresponding number of articles to bepicked has been deposited in the corresponding order container.

The risk that the picking person gets injured is significantly reduced.The removal of the order containers is no longer possible while thepicking person still has his/her hands within the order container. Also,a premature removal of the order containers, without the desired numberof articles being put into the right order container according to thepicking order, can be prevented since the number of the articles whichare put into the order container can be determined through the number ofinterruptions of the beam field.

In accordance with a preferred embodiment, the beam field is arranged,particularly directly, above the openings of the order containers.

The closer the beam field is arranged above the openings of the ordercontainers the easier the location can be reconstructed at which thebeam field has been interrupted by a passage of a hand and/or anarticle, and with the knowledge of the locations of the beam fieldrelative to the order containers, which are located within the buffer,an order container can be assigned. On the other hand, an improvedtemporal assignment is possible since the way, which an article beingput through the beam field has to pass from the beam field to the bottomof the order container, is shorter.

It is particularly preferred if the beam field includes a plurality ofpairs of transmitters and receivers for transmitting beams and receivingthe transmitted beams.

The more beams are forming the beam field, the better the location ofthe interruption of beam can be localized and reconstructed,respectively. The number of transmitter and receiver pairs and itsdistance to each other is directly correlated with the spatialresolution. The spatial resolution can be used for assigning an articleinterrupting the beam field to an order container which is locatedwithin the order container buffer.

It is particularly preferred if the transmitter and receiver pairs arearranged within a strip.

A strip having pairs of transmitters and receivers can be installedabove the order container buffer in an easy manner. An adjustmentnecessary during the installation of a beam field can be reduced to anadjustment of two units, namely the strips which contain the pairs oftransmitters and receivers, instead that the transmitters and receivers,respectively, of each transmitter and receiver pair have to be adjustedseparately with respect to each other.

Further, it is preferred if transmitters of the transmitter and receiverpairs and receivers of the transmitter and receiver pairs are arrangedon a second strip such that a beam field of beams, being particularlyparallel, can be generated between the first and second strip.

By this measure the adjustment of the beam field above the ordercontainer buffer is facilitated.

Additionally, it is an advantage, if transmitters and receivers of thetransmitter and receiver pairs are arranged alternately on one and thesame strip in order to generate with a further strip, which is equallyformed, a crossed beam field.

A crossed beam field has the advantage, in comparison to a beam fieldbeing formed of parallel beams, that also the space between theotherwise parallel beams can be monitored. In dependence on the anglebetween the crossing beams the monitoring location, i.e. the locationwhere the beams cross, can be varied. This is particularly the case ifthe beam field is formed by two oppositely arranged strips.

According to a further preferred embodiment, the beam field can becoupled to means for detecting and evaluating a signal which isgenerated if an article to be picked or a part of the picking person'sbody interrupts a beam of the beam field.

Such means for detecting and evaluating a signal can be a microcomputerwhich, for example, is coupled directly to the electronics of the beamfield in order to directly evaluate the received signals. This measurerelieves the computer, which is responsible for the monitoring of theentire system, by removing processing load therefrom.

Further it is preferred, if the means for detecting and evaluating candetermine the location of the interruption in order to be able to assignthe article, which generates the signal, to an order container.

In this manner, it can be directly determined whether the picking personhas put the article, which is to be picked, into the right ordercontainer within the order container buffer. If necessary, the means fordetecting and evaluating can be coupled directly to the computermonitoring the entire system in order to output a corresponding faultmessage. However, the means can also directly cause the output of asignal, which notifies to the picking person that the concurrent pickingprocess is or was erroneous. The picking person can thus correct theerror directly, i.e. at place. The otherwise erroneous picked ordercontainer thus does not need to be re-picked for repair of error, i.e.it does not need to be brought into the entire course of the systemagain, thereby increasing the entire efficiency of the picking systemsignificantly.

It has proved advantageously if the transmitter and receiver pairsgenerate infrared beams or visible light.

Infrared light and visible light, respectively, is harmless to the eyesof the picking person and thus corresponds to the safety regulations oftoday.

It is particularly preferred if the beam field is formed by at least twoorthogonal transmitter and receiver pairs.

Provision of transmitter and receiver pairs which are orthogonal withrespect to each other increases the already above-mentioned spatialresolution to a specific degree since a second dimension can beintroduced. Hence, not only an x-component, but also an y-component of atwo-dimensional Cartesian beam field can be monitored.

According to a preferred embodiment of the method of the presentinvention a first enabling signal is output when the beams are no longerinterrupted.

The interruption of the beams of the field of beams corresponds, undercertain circumstances, to that state at which the picking person has oneof his/her hands within the order container of the order containerbuffer. As long as the signal is interrupted, no enabling signal can andwill be output which could release the retrieval of the order container.The danger of the picking person becoming injured, due to a retrieval ofan order container within which the picking person has his/her hands, inpractice is reduced to zero.

Further, it is preferred if the first enabling signal is output when theorder container is completely picked.

According to another preferred embodiment, a second enabling signal isoutput when the order container is not completely picked such thatfurther articles, which are to be picked, can be delivered to thepicking station.

It goes without saying that the features mentioned above as well asthose which are still to be explained in the following text can be usednot only in the respectively stated combination but also in othercombinations or on their own, without departing from the scope of thepresent invention.

Exemplary embodiments of the invention are illustrated in the drawing,and will be explained in more detail in the following description. Inthe drawings:

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view of a picking station according tothe present invention;

FIG. 2 shows a two-dimensional field of beams of a picking stationaccording to the present invention, the beam field being formed by twostrips of transmitters and receivers;

FIG. 3 shows a further beam field of a picking station according to thepresent invention, the beam field being formed of two pairs of strips oftransmitters and receivers;

FIG. 4 shows a crossed beam field of a picking station according to thepresent invention; and

FIG. 5 shows a flow diagram of the picking method according to thepresent invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

A picking station according to the invention is hereinafter generallydesignated by reference numeral 10.

In FIG. 1, a schematic perspective view of a picking station 10according to the present invention is shown. The picking station 10includes a buffer 12 intended for order containers 14. Above the buffer12 intended for the order containers 14 a beam field 16 is arrangedwhich includes a plurality of beams 18. The beams 18 are transmitted bytransmitters T and received by receivers R.

A transmitter T and receiver R form a so-called transmitter and receiverpair. Both, the transmitter T and the receiver R can be attached to orlocated within strips 20. However, they can also be providedindividually.

In the example shown in FIG. 1, the transmitters T and receivers R arealternately attached to the strips 20 having an equal distance withrespect to each other such that the beam field 16 is formed by parallelbeams 18. The distance between the transmitters T and receivers R on astrip 20 can be chosen arbitrarily.

The less the distance of the transmitters T and receivers R is, the moretransmitters T and receivers R have to be provided per fixed length ofthe strip 20, and, also, the higher the possible spatial resolution willbecome.

Alternatively, merely transmitters T can be provided on one of thestrips 20, wherein only receivers R will then be provided on theopposite strip 20. The beam field 16 does not absolutely have to beformed by parallel beams 18. It can also be formed by beams beingarbitrarily orientated to each other, which are respectively assigned toa transmitter and receiver pair.

Further, FIG. 1 shows a conveyor system 22 such as a roller track (notshown) or a conveyor belt by which empty order containers 14 can beconveyed to the buffer 12 and picked order containers 14 can beretrieved from the buffer 12.

Even further, a further conveyor system 24 can be provided which conveysthe storage container 26 from a container storage, which is not depictedin FIG. 1, to the picking station 10. The storage containers 26 containarticles 28 which are to be picked. For this purpose, a picking person,being not illustrated, takes out the articles 28 from the storagecontainer 26 and puts these into assigned order containers 14 provided.Such a picking process is schematically depicted by an arrow 29.

In order to enable the putting of the article 28 from the storagecontainer 26 into the order container 14, the picking person musttraverse the beam field 16 at least with the article 28 which is to bepicked. If the articles are highly fragile the picking person, as arule, will manually put the fragile article 28 into the order container14. At the same time, he/she grabs through the beam field 16 withhis/her hand.

Thus, at least one of the beams 18 of the beam field 16, as a generalrule, is interrupted either by a thrown-in article 28, or by a hand oran arm of the picking person. As long as the beam 18 is interrupted, itis obvious that either an article 28 is just given into an ordercontainer 14, or an arm or a hand grabs through the beam field 16.

As will be discussed with reference to FIG. 2, one or more strips 20 canbe connected to means 30 for detecting and evaluating interruptionsignals. The strips 20 can have the means 30 integrated. By the means 30the interruption of a beam 18 can be detected. Signals which will bediscussed below can be output in dependence thereon. Also, the locationof the interruption can be determined by the means 30.

FIG. 2 shows an exemplary embodiment of the beam field 16, wherein theleft strip 20 exclusively comprises receivers and the right strips 20exclusively comprises transmitters. The right strip 20 is coupled to themeans 30 for detecting and evaluating of interruption signals. The means30 are not depicted in more detail. An article 28 is guided through thebeam field 16 of FIG. 2 along an arrow 32.

As will be recognized clearly, the beams 18 in the area of the beamfield 16, in which the article 28 is located, are interrupted. On theleft strip 20 another receiver R can be recognized which does notreceive any beam 18 due to the article 28 which is located within thebeam path. The beam 18 of this transmitter and receiver pair isinterrupted correspondingly. This interruption can be detected andevaluated by the means 30. Hence, an information on the location of theinterruption is obtained. By the knowledge of the attitude of the ordercontainers 14, which are not depicted here, relative to the beam field16, thus the location of the interruption can be at least assigned toone of the order containers 14.

For enhancing the spatial assignment, another pair of strips 20 can,preferably, be orientated substantially orthogonal relative to the firstpair of strips 20. Such an arrangement is shown in FIG. 3. Ifinformation on the third dimension, i.e. the height, is also desired tobe obtained, several beam fields 16 could be arranged, one on top of theother. Such an arrangement is not shown in the figures.

Also, the manner in which the beams 18 in the beam field 16 areorientated to each other can be chosen arbitrarily.

In FIG. 4, for example, a crossed beam field 16 is depicted. In thisconnection, one transmitter and receiver are arranged directly adjacentto each other on the same strip.

With reference to FIG. 5, the picking method according to the presentinvention will be described.

In a first step S1, the storage containers 26 are conveyed, for example,via the conveyor system 24, depicted in FIG. 1, to the picking station10 according to the present invention. Empty order containers 14 are,for example, conveyed by the conveyor system 22, depicted in FIG. 1, tothe buffer 12 intended for the order containers 14. A device forinjection and blocking out, which is not depicted in FIG. 1, takes carethat the order containers 14 are moved into and from the buffer 12,respectively.

In step S2, the processing of a picking order is started. A pickingorder can consist of several articles 28 to be picked. The articles 28can be of the same or different types. As a rule, however, the storagecontainer 26 contain only articles 28 of the same type. If severaldifferent types of articles are to be picked for a picking order, it canbe necessary that several storage containers 26 are conveyed to thepicking station 10 by the conveyor system 24. Subsequently, the pickingperson takes out from the storage containers 26 the number of articles28 corresponding to the picking order. For this purpose, a display canbe provided in the region of the picking station 10, the display is notdepicted in FIG. 1 either and indicates to the picking person how manyarticles 28 are to be taken from the storage container 26.

Further, the storage container 26 itself can be divided additionallysuch that several types of articles can be located in one and the samestorage container 26. For indicating to the picking person which of thedifferent types of articles have to be picked, optionally, an opticalpointing system, which is also not depicted in FIG. 1, can be providedat the picking station 10. For this purpose, for example, a ray of lightcould point from above into the storage container 26 and onto acorresponding type of article. The indication of the destination, i.e.the order containers 14, is similarly, if several order containers 14are located within the buffer 12.

In another step S3, the picking person takes the desired article 28 fromthe storage container 26 and puts it into the predetermined ordercontainer 14.

The type of articles, which are to be picked, itself can be divided intotwo categories with respect to the manner in which they are to bepicked. This is, on the one hand, the so-called “droppable” category,and, on the other hand, the “non-droppable” category. “Droppable”articles can be thrown into the order containers 16 through the beamfield 16 depicted in FIG. 1. “Non-droppable” articles have to be putinto or deposited in the order container 14 by the picking person byhand.

However, in both instances the beam field 18 is either traversed just byan article 28 or by an article 28 in combination with at least a hand oran arm of the picking person.

In another step S4, the means 30 for detecting and evaluating, forexample, request in arbitrarily selectable periodical time periodswhether an interruption of the beam field 16 is present. This request,however, can also be performed by the storage management system beingsuperordinated to the picking system and implementable by a hostcomputer or personal computer.

If at the same time it is determined that the beam field 16 has not beeninterrupted, the system knows that the article 28 to be picked is notlocated yet within the order container 14 assigned thereto. The step S3of taking the article 28 and putting it into the corresponding ordercontainer 14, thus is not terminated yet.

However, if the request S4 results in that the beam field 16 isinterrupted, in another step S5 another request follows by which the(temporal) end of the interruption is queried.

If the request S5 results in that the beam field 16 is stillinterrupted, the system waits for the end of the interruption in anotherstep S6.

If the request S5 however results in that the interruption isterminated, in another request S7 it is determined whether the pickingorder, which is to be carried out at the picking station 10, iscompletely terminated. However, this does not mean that the pickingorder has to be completely terminated. For example, it is also possiblethat the order container 14 is only picked partially at a first pickingstation 10 in order to be subsequently passed to another picking station10 where the picking order can finally be picked completely.

If it is determined during the request S7 that the picking order has notbeen processed yet at the concrete picking station 10, thus, the means30 can, for example, output an enabling signal in step S8.

Due to the enabling signal output in the step S8, in another step S9 anew storage container 26 is conveyed to the picking station 10, theorder container 26 containing further articles 28 which belong to thepicking order. Then, the picking process can be continued at the stepS3.

If the request S7 however results in that the picking order (at thispicking station 10) is completely processed, in another step S10 anotherenabling signal is output. The other enabling signal allows the ordercontainer 14 which now is completely picked, to be retrieved from thebuffer 12. This is depicted by step S11 in FIG. 5. Thus, the pickingprocess is terminated. It is clear that this process can now start fromthe beginning.

1. An order-picking station for picking articles into order containers,comprising a buffer for said buffering order containers into whicharticles are to be picked, said buffer including at least one bufferspace for respectively receiving one order container, wherein above saidbuffer a field of beams is provided for monitoring the picking of saidarticles.
 2. The order-picking station of claim 1, wherein, if severalof said buffer spaces are provided, said buffer spaces are arranged sideby side.
 3. The order-picking station of claim 1, wherein said field ofbeams is arranged above said openings of said order containers.
 4. Theorder-picking station of claim 3, wherein said field of beams isarranged directly above said openings of said order containers.
 5. Theorder-picking station of claim 1, wherein said field of beams includes aplurality of transmitter and receiver pairs for transmitting beams andreceiving said transmitted beams.
 6. The order-picking station of claim5, wherein said transmitter and receiver pairs are arranged in a strip.7. The order-picking station of claim 6, wherein transmitters of saidtransmitter and receiver pairs are arranged on a first strip, andreceivers of said transmitter and receiver pairs are arranged on asecond strip for generating said field of beams between said first andsecond strips.
 8. The order-picking station of claim 7, wherein saidbeams are parallel.
 9. The order-picking station of claim 7, whereinsaid transmitters and receivers of said transmitter and receiver pairsare arranged alternately on one and the same strip for generating acrossed field of beams with another strip being formed equally.
 10. Theorder-picking station of claim 1, wherein said field of beams can becoupled to a means for detecting and evaluating a signal which isgenerated if an article to be picked, or if a part of a body of apicking person interrupts a beam of said field of beams.
 11. Theorder-picking station of claim 10, wherein a location of saidinterruption is determinable by said means for detecting and evaluating,in order to assign an order container to an article which generates saidsignal.
 12. The order-picking station of claim 1, wherein saidtransmitter and receiver pairs generate infrared beams.
 13. Theorder-picking station of claim 1, wherein said transmitter and receiverpairs generate visible light.
 14. The order-picking station of claim 1,wherein said field of beams is formed of at least two transmitter andreceiver pairs being orthogonal to each other.
 15. The order-pickingstation of claim 1, wherein a further conveyor system for automaticallyconveying said order containers, and a controlling device forcontrolling the automatized conveyance are provided.
 16. A method fororder-picking, at a picking station for picking articles into ordercontainers, said order picking station comprising a buffer for bufferingsaid order containers into which articles are to be picked, said bufferincluding at least one buffer space for respectively receiving one ordercontainer, wherein above said buffer a field of beams is provided formonitoring the picking of said articles, of articles into said ordercontainers storable within said buffer, comprising the steps: generatingsaid field of beams above said buffer; detecting an interruption signalwhich is generated by an interruption of said field of beams; andoutputting a first enabling signal for allowing retrieval of said ordercontainer from said buffer.
 17. The method of claim 16, wherein beams ofsaid field of beams are interrupted by an article to be picked.
 18. Themethod of claim 16 or 17, wherein beams of said field of beams areinterrupted by a hand of a picking person.
 19. The method of claim 16,wherein a first enabling signal is output if said beams are no longerinterrupted.
 20. The method of claim 19, wherein said first enablingsignal is output if said order container is completely order-picked. 21.The method of claim 20, wherein a second enabling signal is output ifsaid order container is not completely order-picked so that furtherarticles to be picked are deliverable to said picking station.
 22. Anorder-picking system having a picking station for picking articles intoorder containers, said order picking station comprising a buffer forbuffering said order containers into which articles are to be picked,said buffer including at least one buffer space for respectivelyreceiving one order container, wherein above said buffer a field ofbeams is provided for monitoring the picking of said articles, ofarticles into said order containers storable within said buffer.